Progressive cutter size and spacing in core bit inner diameter

ABSTRACT

A core drilling bit comprising a tubular body having an inner diameter, an outer diameter, and a leading face spanning from the inner diameter to the outer diameter; and a plurality of cutters mounted in the face; wherein cutters mounted along the inner diameter vary in configuration. For example, the cutters may be progressively larger along the inner diameter. The interior edges of the cutters along the inner diameter may be aligned in a circle with their outer edges being aligned in a spiral. The leading edges of the cutters along the inner diameter may be aligned at a constant depth, a progressively shallower depth, or a progressively deeper depth. The cutters may be spaced progressively wider or narrower along the inner diameter.

CROSS REFERENCE TO RELATED APPLICATIONS

None.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The inventions disclosed and taught herein relate generally to earth boring drill bits; and more specifically related to earth boring core drill bits.

2. Description of the Related Art

U.S. Pat. No. 4,981,183 describes a “coring apparatus which includes a drill bit and a receiving member. The drill bit includes discrete cutting elements for cutting the outer dimension of the core. The receiving member is adapted to lie proximate to the discrete cutting surfaces and to receive the core as it leaves the cutting surfaces. Additionally, drilling fluid is directed away from the cut core.”

U.S. Pat. No. 7,048,081 describes a “superabrasive cutting element for use with a drill bit for drilling subterranean formations and having a superabrasive table, or cutting face, in which a conglomerate of superabrasive particles is dispersed and bonded, or sintered, and in which at least one exposed cutting region of the superabrasive table develops a rough, asperital surface for improving the cutting efficiency of the drill bit, particularly in but not limited to relatively hard, relatively nonabrasive formations. The superabrasive table may include superabrasive particles of substantially differing size, or quality or a combination of differing size and quality. A rotary drill bit including cutting elements embodying the present invention is also disclosed.”

U.S. Pat. No. 7,341,118 describes a “rotating dry drilling bit for low thrust drilling of an annular bore hole into a body of rock and obtaining an extremely small diameter core sample comprises a bit crown moulded to the end of an annular steel body. The bit crown comprises a plurality of radially extending channels and a plurality of evenly spaced radially extending cutting blades surrounding an annulus. The bit crown is a hard metal matrix formed onto the bottom end of the annular steel body using a powdered metallurgy process. Embedded within each cutting blade are natural and synthetic diamonds. A reverse auger mechanism within the annulus removes cuttings from the annulus and the surface of the bit crown.”

The inventions disclosed and taught herein are directed to an improved design for an earth boring core drill bit.

BRIEF SUMMARY OF THE INVENTION

The present invention includes a core drilling bit comprising a tubular body having an inner diameter, an outer diameter, and a leading face spanning from the inner diameter to the outer diameter; and a plurality of cutters mounted in the face; wherein cutters mounted along the inner diameter vary in configuration. The cutters may be progressively larger along the inner diameter. The interior edges of the cutters along the inner diameter may be aligned in a circle. The outer edges of the cutters along the inner diameter may be aligned in a spiral. The leading edges of the cutters along the inner diameter may be aligned at a constant depth. The leading edges of the cutters along the inner diameter may be aligned at a progressively shallower depth. The leading edges of the cutters along the inner diameter may be aligned at a progressively deeper depth. The cutters may be spaced progressively wider along the inner diameter. The cutters may be spaced progressively narrower along the inner diameter.

Thus, in one embodiment, the cutter size gradually increases from inner diameter (ID) outward thus creating a spiral/stepping effect. This improved design increases diamond volume, effective work rate of inner diameter cutters, allows a smoother transition of cutters, and increases the quantity of PDC cutters to effectively cut formation as well as trimming the core. The new design involves an incremental increase in cutter size emanating from the inner diameter of the bit outwards. For example, in this embodiment, a first cutter might be 11 mm in diameter, with a second cutter being 13 mm in diameter, and a third cutter being 16 mm in diameter. The remaining cutters on the bit face may be 19 mm cutters. All cutters smaller than 19 mm may aid in effectively cutting core and formation.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates a cross sectional elevation view of a core drilling bit utilizing certain aspects of the present inventions;

FIG. 2A illustrates plan view of a first embodiment of the bit utilizing certain aspects of the present inventions;

FIG. 2B illustrates a cutter profile of the first embodiment of the bit;

FIG. 2C illustrates an artificially straightened cutting path of a plurality of cutters of the first embodiment of the bit;

FIG. 3A illustrates plan view of a second embodiment of the bit utilizing certain aspects of the present inventions;

FIG. 3B illustrates a cutter profile of the second embodiment of the bit; and

FIG. 3C illustrates an artificially straightened cutting path of a plurality of cutters of the second embodiment of the bit.

DETAILED DESCRIPTION

The Figures described above and the written description of specific structures and functions below are not presented to limit the scope of what Applicants have invented or the scope of the appended claims. Rather, the Figures and written description are provided to teach any person skilled in the art to make and use the inventions for which patent protection is sought. Those skilled in the art will appreciate that not all features of a commercial embodiment of the inventions are described or shown for the sake of clarity and understanding. Persons of skill in this art will also appreciate that the development of an actual commercial embodiment incorporating aspects of the present inventions will require numerous implementation-specific decisions to achieve the developer's ultimate goal for the commercial embodiment. Such implementation-specific decisions may include, and likely are not limited to, compliance with system-related, business-related, government-related and other constraints, which may vary by specific implementation, location and from time to time. While a developer's efforts might be complex and time-consuming in an absolute sense, such efforts would be, nevertheless, a routine undertaking for those of skill in this art having benefit of this disclosure. It must be understood that the inventions disclosed and taught herein are susceptible to numerous and various modifications and alternative forms. Lastly, the use of a singular term, such as, but not limited to, “a,” is not intended as limiting of the number of items. Also, the use of relational terms, such as, but not limited to, “top,” “bottom,” “left,” “right,” “upper,” “lower,” “down,” “up,” “side,” and the like are used in the written description for clarity in specific reference to the Figures and are not intended to limit the scope of the invention or the appended claims.

Applicants have created a core drilling bit comprising a tubular body having an inner diameter, an outer diameter, and a leading face spanning from the inner diameter to the outer diameter; and a plurality of cutters mounted in the face; wherein cutters mounted along the inner diameter vary in configuration. The cutters may be progressively larger along the inner diameter. The interior edges of the cutters along the inner diameter may be aligned in a circle. The outer edges of the cutters along the inner diameter may be aligned in a spiral. The leading edges of the cutters along the inner diameter may be aligned at a constant depth. The leading edges of the cutters along the inner diameter may be aligned at a progressively shallower depth. The leading edges of the cutters along the inner diameter may be aligned at a progressively deeper depth. The cutters may be spaced progressively wider along the inner diameter. The cutters may be spaced progressively narrower along the inner diameter.

FIG. 1 is a cross sectional elevation view of a core drilling bit 10 utilizing certain aspects of the present inventions. The bit 10 includes a tubular, or cylindrical, body 12 presenting an inner diameter 14, an outer diameter 16, and a leading face 18 spanning from the inner diameter 14 to the outer diameter 16. FIG. 1 is intended as a simplified illustration to assist in readily understanding the present invention. The actual bit 10 may be shaped with greater complexity. For example, the bit 10 may be shaped similar to, and share other characteristics with, those shown in U.S. Pat. No. 4,981,183 and/or U.S. Pat. No. 7,341,118, both of which are incorporated herein by specific reference.

The inner diameter 14 forms and defines a core being drilled. The outer diameter 16 forms and defines a hole excavated from the earth. The face 18 is preferably curved. The face 18 may be uniformly curved, as shown in FIG. 1. Alternatively, the face 18 may be distorted toward the inner diameter 14 or outer diameter 16. In either case, as will be discussed in greater detail below, the face 18 preferably includes a plurality of cutters 20 mounted thereon.

The cutters 20 may be similar to those described in U.S. Pat. No. 7,048,081, incorporated herein by specific reference. While the cutters 20 shown in the instant specification are cylindrical, with a circular cross-section, other shapes may be used. For example, the cutters 20 may be oval, rectangular, and/or triangular. The cutters 20 may also be tapered along their length.

In any case, referring also to FIG. 2A, the cutters 20 cut the earth formation leaving a core which may be extracted for analysis. So that the inner diameter 14 of the bit 10 does not rub excessively, needlessly increasing the specific energy required to drill the core, and/or damage the core, the cutters 20 preferably cut the core to a core diameter 14 a slightly smaller than the inner diameter 14 of the bit 10. This core diameter 14 a is achieved by inner diameter (ID) cutters 20 a.

The face 18 may be relatively smooth, or continuous, around the body 12, or may include one or more blades 22. In one embodiment, the cutters 20,20 a are mounted on a leading edge of each blade 22. For example, in the embodiment shown in FIG. 2A, wherein the bit 10 is designed to rotate counter-clockwise, the cutters 20,20 a are mounted on a counter-clockwise most edge of each blade 22. In other embodiments, such as those designed to rotate clockwise, the cutters 20,20 a may be mounted on a clockwise most edge of each blade 22. As shown in FIG. 2A, the blades 22 may or may not have similar or identical numbers of cutters 20,20 a thereon.

The blades 22 are shown as having flat sides, or edges, for simplicity. However, it should be understood that the blades 22 may have curved edges. For example, the leading edge of each blade 22 may exhibit a forward or reverse spiral.

The cutters 20,20 a may be of different sizes. For example, in some embodiments, the ID cutters 20 a may between approximately 8 mm and 19 mm in diameter. More specifically, in one embodiment, a first ID cutter 20 a is approximately 11 mm in diameter, with a second ID cutter 20 a being approximately 13 mm in diameter, and a third ID cutter 20 a being approximately 16 mm in diameter. In another embodiment, a first ID cutter 20 a is approximately 8 mm in diameter, with a second ID cutter 20 a being approximately 11 mm in diameter, a third ID cutter 20 a being approximately 13 mm in diameter, and a fourth ID cutter 20 a being approximately 16 mm in diameter. The remaining cutters 20,20 a may be approximately 19 mm in diameter. In alternative embodiments, the cutters 20,20 a may be between 5 mm and 30 mm. The size progression may or may not be uniform. Furthermore, the ID cutters 20 a may be smaller, larger, or the same size as the other cutters 20. As shown in FIG. 2A, there may be one, two, three, four, or more ID cutters 20 a along the inner diameter 14.

If one were to rotate the bit 10 through a single plane, the cutters 20,20 a would overlap and exhibit the cutter profile shown in FIG. 2B. As can also be seen in FIG. 2B, in one embodiment, the ID cutters 20 a overlap to a more significant extent than do the remaining cutters 20. More specifically, the ID cutters 20 a are preferably aligned to the core diameter 14 a long their inner most edge. However, in one embodiment, successive ID cutters 20 a are larger, as discussed above. Therefore, each successive ID cutter 20 a also cuts the formation incrementally more outward from the core diameter 14 a.

It can be seen that the cutters 20, 20 a trace a generally circular path through the earth formation. If one were to straighten that path, the ID cutters 20 a would exhibit the cutting path shown in FIG. 2C. Thus, in one embodiment, the inner most edge of each ID cutter 20 a follows the same path as the ID cutter 20 a before. In this manner, each ID cutter 20 a cuts along the core diameter 14 a, which is slightly smaller than the inner diameter 14 of the bit 10.

Since the ID cutters may be aligned adjacent the core diameter 14 a, as discussed above, the inner most edges, or interior edges, of the ID cutters 20 a may trace, or be aligned, in a circle. Furthermore, since the ID cutters 20 a may be progressively larger, as discussed above, the outer most edges, or outer edges, of the ID cutters 20 a may trace, or be aligned in, a spiral. Additionally, since the ID cutters 20 a may be progressively larger, as discussed above, leading edges of successive cutters 20,20 a may be aligned at, and therefore cut the formation at, a progressively deeper depth. However, in alternative embodiments, the cutters 20,20 a may be aligned at, and therefore cut the formation at, a progressively shallower, or even constant, depth.

In another embodiment, referring also to FIG. 3A, each blade 22 may or may not include one or more cutters 20 along the inner diameter 14 and adjacent the core diameter 14, such as the ID cutters 20 a discussed above. The blades 22, and/or the cutters 20,20 a, may or may not be evenly spaced along the face 18 of the bit 10. For example, as shown in FIG. 3A, the blades, and thus the cutters 20,20 a mounted thereon may exhibit a variable spacing with respect to one another.

If one were to rotate the bit 10 through a single plane, the cutters 20,20 a would overlap and exhibit the cutter profile shown in FIG. 3B. As can be seen, in FIG. 3B, if identically sized ID cutters 20 a are used, they might overlap completely. However, in alternative embodiments, leading edges of the cutters 20,20 a may be aligned at, and therefore cut the formation at, a progressively deeper, shallower, or even constant, depth.

As discussed above, the cutters 20, 20 a trace a generally circular path through the earth formation. If one were to straighten that path, the ID cutters 20 a would exhibit the cutting path shown in FIG. 3C. Thus, in one embodiment, the inner most edge of each ID cutter 20 a follows the same path as the ID cutter 20 a before. In this manner, each ID cutter 20 a cuts along the core diameter 14 a, which is slightly smaller than the inner diameter 14 of the bit 10.

Since the ID cutters may be aligned adjacent the core diameter 14 a, as discussed above, the inner most edges, or interior edges, of the ID cutters 20 a may trace, or be aligned in a circle. Furthermore, since the ID cutters 20 a may be of similar, or identical, size the outer most edges, or outer edges, of the ID cutters 20 a may also trace, or be aligned in a circle. However, because the blades 22 varying in spacing so too may the cutters 20,20 a. Thus, as shown in FIG. 3C, the spacing between a first and second ID cutter 20 a may be narrower, or wider, than the spacing between successive pairs, such as the second and a third ID cutter 20 a and/or the third and a fourth ID cutter 20 a. The spacing between successive pairs of cutters 20,20 a may or may not increment uniformly. As may also be seen in FIG. 3B, any such spacing pattern may repeat.

It can be seen that the present invention thus may be utilized to maximize diamond volume along the inner diameter 14 to maintain core integrity as well as effectively cut the earth formation. The present invention may therefore increase diamond volume, effective work rate of the ID cutters 20 a, allow a smoother transition of cutters 20,20 a, and increase the quantity of cutters 20,20 a to effectively cut the earth formation, as well as properly trim the core. Maximum density spacing may be preferred for optimum diamond volume within manufacturing limits, in terms of spacing between the blades 18, and thus the cutters 20,20 a, and/or in terms of the cutters 20,20 a along each blade 18. Cutter exposure from the bit body 12 is not expected to, buy may in certain application, exceed more than approximately one half of the cutter diameter, and is therefore expected to be less than one half inch.

Other and further embodiments utilizing one or more aspects of the inventions described above can be devised without departing from the spirit of Applicant's invention. For example, in certain applications, the cutters may be progressively smaller along the inner diameter and/or share a common circular outer diameter, with a spiral inner diameter. Additionally, or alternatively, the cutters along the outer diameter may vary in configuration, as discussed above, with the cutters along the inner diameter being constant or varying in configuration, as discussed above. Further, the various methods and embodiments of the present invention can be included in combination with each other to produce variations of the disclosed methods and embodiments. Discussion of singular elements can include plural elements and vice-versa.

The inventions have been described in the context of preferred and other embodiments and not every embodiment of the invention has been described. Obvious modifications and alterations to the described embodiments are available to those of ordinary skill in the art. The disclosed and undisclosed embodiments are not intended to limit or restrict the scope or applicability of the invention conceived of by the Applicants, but rather, in conformity with the patent laws, Applicants intend to fully protect all such modifications and improvements that come within the scope or range of equivalent of the following claims. 

1. A core drilling bit comprising: a tubular body having an inner diameter, an outer diameter, and a leading face spanning from the inner diameter to the outer diameter; and a plurality of cutters mounted to the face; wherein cutters mounted along the inner diameter vary in configuration.
 2. The bit of claim 1, wherein the cutters are progressively larger along the inner diameter.
 3. The bit of claim 2, wherein interior edges of the cutters along the inner diameter are aligned in a circle.
 4. The bit of claim 2, wherein outer edges of the cutters along the inner diameter are aligned in a spiral.
 5. The bit of claim 2, wherein leading edges of the cutters along the inner diameter are aligned at a constant depth.
 6. The bit of claim 2, wherein leading edges of the cutters along the inner diameter are aligned at a progressively shallower depth.
 7. The bit of claim 2, wherein leading edges of the cutters along the inner diameter are aligned at a progressively deeper depth.
 8. The bit of claim 1, wherein the cutters are spaced progressively wider along the inner diameter.
 9. The bit of claim 1, wherein the cutters are spaced progressively narrower along the inner diameter.
 10. A core drilling bit comprising: a tubular body having an inner diameter, an outer diameter, and a leading face spanning from the inner diameter to the outer diameter; and a plurality of cutters mounted to the face; wherein cutters mounted along the inner diameter are sized and spaced differently along the inner diameter.
 11. The bit of claim 10, wherein the cutters are progressively larger along the inner diameter.
 12. The bit of claim 11, wherein interior edges of the cutters along the inner diameter are aligned in a circle.
 13. The bit of claim 11, wherein outer edges of the cutters along the inner diameter are aligned in a spiral.
 14. The bit of claim 11, wherein leading edges of the cutters along the inner diameter are aligned at a constant depth.
 15. The bit of claim 11, wherein leading edges of the cutters along the inner diameter are aligned at a progressively shallower depth.
 16. The bit of claim 11, wherein leading edges of the cutters along the inner diameter are aligned at a progressively deeper depth.
 17. The bit of claim 10, wherein the cutters are spaced progressively wider along the inner diameter.
 18. The bit of claim 10, wherein the cutters are spaced progressively narrower along the inner diameter.
 19. A core drilling bit comprising: a tubular body having an inner diameter, an outer diameter, and a leading face spanning from the inner diameter to the outer diameter; and a plurality of cutters mounted in the face; wherein cutters mounted along the inner diameter are progressively larger and spaced progressively wider along the inner diameter.
 20. The bit of claim 19, wherein interior edges of the cutters along the inner diameter are aligned in a circle and outer edges of the cutters along the inner diameter are aligned in a spiral. 